Zur Komplexchemie von Cyclopentadienyl‐Liganden mit Oligoethylenglycolether‐Tentakeln

On the Complex Chemistry of Cyclopentadienyl Ligands with Oligoethylene Glycol Ether Tentacles Herrn Professor Eckehard V. Dehmlow zum 60. Geburtstag gewidmet. The potassium cyclopentadienides KCp′[SiMe2(OCH2CH2)m1‐OCH3]n (2) react with trimethyltin chloride to give the respective stannanes Me3SnCp′[SiMe2(OCH2CH2)mOCH3]n (3a–e). Reaction of 2a–e with iron(II) chloride affords the ferrocenes Fe{Cp′[SiMe2(OCH2CH2)mOCH3]n}2 (4a–e), which are soluble in solvents of all polarities. 4a–d were investigated with respect to their ability to act as podands for alkaline metal cations. 4c, d prove to be much better podants than 4a, b; 4a, c show a certain selectivity for K+, 4b, d show a preference for Cs+. Without rigorous exclusion of moisture, 4e yeilds the tetrasiladioxa[3](1,1‐)[3](3,3‐)ferrocenophane 5 upon prolonged standing at room temperature. The structure of 5 was determined by a single‐crystal X‐ray diffraction study. The molecule is essentially unstrained with the cyclopentadienyl rings being exactly parallel to each other; the distance between the iron atom and the ring centroid is 165 pm.